parser.c

#include "shell.h"

int initTokensTable(char *line);
int tokensIsEmpty();
token *tokensGetNextElement();
token *tokensCheckNextElement();
void tokensSkipElement();

static job *parseJob();
static process *parseProcess(char **infile, char **outfile, char **appfile);

int isControlSymbol(char c)
{
    return (c == '|' || c == ';' || c == '&' || c == '>' || c == '<');
}

/**
 * ÏÖÉÄÁÅÍÙÊ ××ÏÄ: job1 [&;] job2 [&;] ...
 * ÈÜÎÄÌÉÔ '&', ';', Ô.Ë. ÜÔÏ ÏÓÎÏ×ÎÏÊ ÜÌÅÍÅÎÔ ÄÌÑ ÒÁÚÄÅÌÅÎÉÑ ÚÁÄÁÎÉÊ
 * ÄÏÇÏ×ÏÒÅÎÎÏÓÔØ: ËÁÖÄÁÑ ÆÕÎËÃÉÑ ÄÏÌÖÎÁ "ÐÒÏÞÉÔÙ×ÁÔØ" ÔÏÌØËÏ ÔÅ ÔÏËÅÎÙ, ËÏÔÏÒÙÅ ÏÎÁ ÈÜÎÄÌÉÔ
*/
int parseline(char *line)
{
    int tokens = initTokensTable(line);
    if (tokens == -1)
        return 0;

    job *currentJob;
    for (currentJob = first_job; currentJob && currentJob->next; currentJob = currentJob->next)
        ;

    /* ÕÓÌÏ×ÉÅ ÏËÏÎÞÁÎÉÑ ÓÔÒÏËÉ - ÏÔÓÕÔÓÔ×ÉÅ ÔÏËÅÎÏ× */
    while (!tokensIsEmpty())
    {
        token *t = tokensCheckNextElement();
        switch (t->type)
        {
        case AMPERSAND:
            if (currentJob)
            {
                currentJob->foreground = 0;
                tokensSkipElement();
            }
            else
            {
                /* ÐÙÔÁÅÍÓÑ ÓÄÅÌÁÔØ ÆÏÎÏ×ÙÍ ÚÁÄÁÎÉÅ, ËÏÔÏÒÏÅ ÐÏ ÆÁËÔÕ ÎÅ ÓÕÝÅÓÔ×ÕÅÔ */
                fprintf(stderr, "syntax error\n");
                return 0;
            }
            break;
        case SEMICOLON:
            tokensSkipElement();
            break;
        default:
            if (!currentJob)
            {
                if((first_job = currentJob = parseJob()) == 0){
                    return 0;
                }
            }
            else
            {
                if((currentJob->next = parseJob()) == 0){
                    return 0;
                }
                currentJob = currentJob->next;
            }
            break;
        }
    }

    return tokens;
}

/**
 * ÏÖÉÄÁÅÍÙÊ ×ÈÏÄ: "proc1 | proc2 | ... | procn"
 * ÈÜÎÄÌÉÔ '|', Ô.Ë. ÜÔÏ ÏÓÎÏ×ÎÏÊ ÓÔÒÏÉÔÅÌØÎÙÊ ÜÌ-Ô ÄÌÑ ÚÁÄÁÎÉÊ
 * ÏÂÒÁÂÁÔÙ×ÁÅÔ <> ÄÌÑ ÐÅÒ×ÏÇÏ É ÐÏÓÌÅÄÎÅÇÏ ÐÒÏÃÅÓÓÁ × ÔÒÕÂÅ??
*/
static job *parseJob()
{
    char *infile = 0, *outfile = 0, *appfile = 0;
    job *j = (job *)malloc(sizeof(job));
    j->next = 0;
    j->stdinno = STDIN_FILENO;
    j->stdoutno = STDOUT_FILENO;
    j->foreground = 1;
    j->pgid = 0;
    j->launched = 0;
    j->notified = 0;
    j->command = 0;
    j->builtin = 0;
    process *currentProcess = j->first_process = 0;

    token *t = tokensCheckNextElement();
    /* ÕÓÌÏ×ÉÑ ÏËÏÎÞÁÎÉÑ ÚÁÄÁÎÉÑ - ÔÏËÅÎÙ ;& ÉÌÉ ÏÔÓÕÔÓÔ×ÉÅ ÔÏËÅÎÏ× */
    while (!tokensIsEmpty() && t->type != AMPERSAND && t->type != SEMICOLON)
    {
        switch (t->type)
        {
        case PIPE:
            tokensSkipElement();
            if (currentProcess && !j->builtin)
            {
                /* ÐÅÒÅÈÏÄÉÍ ÐÏ ÔÒÕÂÅ, ÐÒÏÃÅÓÓ ÓÌÅ×Á ÕÖÅ ÂÙÌ */
                /* ÓÐÒÁ×Á ÏÔ ÐÁÊÐÁ ÏÂÑÚÁÔÅÌØÎÏ ÄÏÌÖÅÎ ÂÙÔØ ÄÒÕÇÏÊ ÐÒÏÃÅÓÓ */
                if (!(!tokensIsEmpty() && t->type != AMPERSAND && t->type != SEMICOLON))
                {
                    fprintf(stderr, "syntax error\n");
                    return 0;
                }
                if((currentProcess->next = parseProcess(&infile, &outfile, &appfile)) == 0) {
                    return 0;
                }
                currentProcess = currentProcess->next;
            }
            else
            {
                fprintf(stderr, "syntax error\n");
                return 0;
            }
            break;
        default:
            /* ÜÔÏ ÐÅÒ×ÙÊ ÐÒÏÃÅÓÓ */
            if((currentProcess = j->first_process = parseProcess(&infile, &outfile, &appfile)) == 0) {
                return 0;
            }
            if (strcmp(j->first_process->argv[0], "jobs") == 0 ||
                strcmp(j->first_process->argv[0], "fg") == 0 ||
                strcmp(j->first_process->argv[0], "bg") == 0 ||
                strcmp(j->first_process->argv[0], "cd") == 0)
            {
                j->builtin = 1;
            }
            break;
        }
        t = tokensCheckNextElement();
    }
    /* ÚÄÅÓØ ÍÙ ×ÎÅÚÁÐÎÏ ÏÔËÒÙ×ÁÅÍ ÆÁÊÌÙ. ÌÏÇÉËÁ ËÏÎÅÞÎÏ ÎÅ ÁÈÔÉ, ÎÏ ÌÕÞÛÅÇÏ ÍÅÓÔÁ ÐÏËÁ ÎÅ ÎÁÛÌÏÓØ.
       ÐÏ ËÏÎÔÒÁËÔÕ ÍÙ ÄÏÇÏ×ÏÒÉÌÉÓØ ÈÒÁÎÉÔØ × ÚÁÄÁÎÉÉ ÒÕÞËÉ ÆÁÊÌÏ×. */
    if (infile)
    {
        if ((j->stdinno = open(infile, O_RDONLY | O_CLOEXEC)) == -1)
        {
            perror(infile);
            exit(1);
        }
    }
    if (outfile)
    {
        if ((j->stdoutno = open(outfile, O_CREAT | O_TRUNC | O_WRONLY | O_CLOEXEC, 0644)) == -1)
        {
            perror(outfile);
            exit(1);
        }
    }
    else if (appfile)
    {
        if ((j->stdoutno = open(appfile, O_CREAT | O_APPEND | O_WRONLY | O_CLOEXEC, 0644)) == -1)
        {
            perror(appfile);
            exit(1);
        }
    }
    return j;
}

/**
 * ÏÖÉÄÁÅÍÙÊ ×ÈÏÄ: "arg0 arg1 ... argn [<,>,>>]"
 * ÅÓÌÉ infile != 0, ÔÕÄÁ ÎÕÖÎÏ ÐÏÌÏÖÉÔØ <
 * ÁÎÁÌÏÇÉÞÎÏ ÄÌÑ outfile, appfile, errfile.
 * ÅÓÌÉ ÁÒÇÕÍÅÎÔ 0, ÎÏ ×ÓÔÒÅÞÁÅÔÓÑ ÐÅÒÅÎÁÐÒÁ×ÌÅÎÉÅ ÅÇÏ ÔÉÐÁ - syntax error
*/
static process *parseProcess(char **infile, char **outfile, char **appfile)
{
    process *p = (process *)malloc(sizeof(process));
    p->nargs = 0;
    p->next = 0;
    p->argv[0] = (char *)NULL;
    p->completed = 0;
    p->stopped = 0;
    p->stderrno = STDERR_FILENO;
    char * errfile = 0;
    token *t = tokensCheckNextElement();
    while (!tokensIsEmpty() && t->type != SEMICOLON && t->type != AMPERSAND && t->type != PIPE)
    {
        switch (t->type)
        {
        case REALLYRIGHTARROW:
            /* appfile */
            tokensSkipElement();
            t = tokensGetNextElement();
            if (!t || t->type != WORD)
            {
                fprintf(stderr, "after >> should be filename\n");
                return 0;
            }
            *appfile = t->place;
            break;
        case ERRORRIGHTARROW:
            /* errfile */
            tokensSkipElement();
            t = tokensGetNextElement();
            if (!t || t->type != WORD)
            {
                fprintf(stderr, "after 2> should be filename\n");
                return 0;
            }
            errfile = t->place;
            break;
        case RIGHTARROW:
            /* outfile */
            tokensSkipElement();
            t = tokensGetNextElement();
            if (!t || t->type != WORD)
            {
                fprintf(stderr, "after > should be filename\n");
                return 0;
            }
            *outfile = t->place;
            break;
        case LEFTARROW:
            /* infile */
            tokensSkipElement();
            t = tokensGetNextElement();
            if (!t || t->type != WORD)
            {
                fprintf(stderr, "after < should be filename\n");
                return 0;
            }
            *infile = t->place;
            break;
        default:
            p->argv[p->nargs++] = t->place;
            p->argv[p->nargs] = (char *)NULL;
            tokensSkipElement();
            break;
        }
        t = tokensCheckNextElement();
    }

    if(errfile)
    {
        if ((p->stderrno = open(errfile, O_CREAT | O_TRUNC | O_WRONLY | O_CLOEXEC, 0644)) == -1)
        {
            perror(errfile);
            exit(1);
        }
    }

    return p;
}